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pipe with buoyantFoam buoyancy, boundary conditions

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Old   June 15, 2009, 08:58
Default pipe with buoyantFoam buoyancy, boundary conditions
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Dear all,

I try to simulate a pipe flow axis-symmetric. The mesh was generated in Gambit (one cell thick) and converted with fluentMeshToFoam and scaled. After it was made axis-symmetric with the application makeAxialMesh. When running with icoFoam there are no solving problems, but I want to use a heated wall with buoyancy effects, the acceleration is parallel to the pipe. And there I get no solution...

The boundary layers are:

* inlet Eingang
* outlet Ausgang
* wedge (frontAndBack)
* wall (oben)
* axis

The Fluid is air and I try to solve without implementation of turbulence modelling.

But what kind of boundary conditions are neccessary so solve. I read a lot in the forum and tested...


p

dimensions [1 -1 -2 0 0 0 0];

internalField uniform 100000;

boundaryField
{
oben
{
type calculated;
value uniform 100000;
}

axis
{
type empty;
}

frontAndBack
{
type empty;
}

eingang
{
type zeroGradient;
}

ausgang
{
type calculated;
value uniform 100000;
}

symmetry_pos
{
type wedge;
}

symmetry_neg
{
type wedge;
}

symmetry
{
type empty;
}
}

// ************************************************** ***********************

pd

dimensions [1 -1 -2 0 0 0 0];

internalField uniform 0;

boundaryField
{
oben
{
type fixedFluxBuoyantPressure;
value uniform 0;
}

axis
{
type empty;
}

frontAndBack
{
type empty;
}

eingang
{
type zeroGradient;
}

ausgang
{
type fixedFluxBuoyantPressure;
value uniform 0;
}

symmetry_pos
{
type wedge;
}

symmetry_neg
{
type wedge;
}

symmetry
{
type empty;
}
}

// ************************************************** ***********************


U

dimensions [0 1 -1 0 0 0 0];

internalField uniform (3 0 0);

boundaryField
{
oben
{
type fixedValue;
value uniform (0 0 0);
}

symmetry
{
type empty;
}

axis
{
type empty;
}

frontAndBack
{
type empty;
}

ausgang
{
type zeroGradient;
}

eingang
{
type fixedValue;
value uniform (3 0 0);
}

symmetry_pos
{
type wedge;
}

symmetry_neg
{
type wedge;
}
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

T

dimensions [0 0 0 1 0 0 0];

internalField uniform 300;

boundaryField
{
oben
{
type fixedValue;
value uniform 300;
}

symmetry
{
type empty;
}

axis
{
type empty;
}

frontAndBack
{
type empty;
}

ausgang
{
type zeroGradient;
}

eingang
{
type fixedValue;
value uniform 300;
}

symmetry_pos
{
type wedge;
}

symmetry_neg
{
type wedge;
}
}

// ************************************************** *********************** //

Could someone please give me a hint.

Thanks a lot, Thomas Baumann
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